1. Technical Field
This disclosure relates generally to active clearance control between a rotor blade and a shroud.
2. Background Information
A turbine engine may include a fan section, a compressor section, a combustor section and a turbine section. Rotor blades in the compressor and the turbine sections may be surrounded by annular shrouds. To reduce leakage between tips of the rotor blades and the shrouds, the turbine engine may include an active clearance control (ACC) system.
A typical active clearance control system is configured to change a diameter of a base structure to which a shroud is attached and arranged within. By changing the diameter of the base structure, the active clearance control system may change the diameter of the shroud and thereby change clearance between the shroud and the rotor blade tips.
The active clearance control system may be controlled using a universal control logic. This universal control logic may be derived from tests performed on a test turbine engine, and then applied to the active clearance control systems of all turbine engines of a particular model. Utilizing such a universal control logic, however, cannot account for variations between the turbine engines. For example, slight variations in the components of the active clearance control system and/or of the turbine engines may lead to slightly different engine characteristics. As a result, while the universal control logic may be particularly well suited for one turbine engine (particularly the test turbine engine), the universal control logic may operate another turbine engine with too much clearance and still another turbine engine with too little clearance. Too much and too little clearance may both reduce turbine engine efficiency. Too little clearance may also lead to rubbing and result in premature wear of the shrouds and/or the rotor blades.
There is a need in the art for improved systems and methods for controlling clearance between a rotor blade tip and a shroud.